During courtship, females fan out their violet pelvic fin, suggesting that the fin is actively used during mate choice.

The researchers found that males clearly preferred females with a larger pelvic fin and that pelvic fins grew in a more disproportionate way than other fins on female fish.

“Our study is, to our knowledge, the first to show that male choice might scale the proportions of a female sexual trait, and therefore has implications for the understanding of the relationship of female traits with body size,” Baldauf said.

The study has been published in the open access journal BMC Evolutionary Biology. (ANI)